594

DYEING AND CALICO PRINTING.

whites are cleared. The pieces are then well washed, and next cleared in asoap-beck, at 120° F., for fifteen minutes, using about 4 ozs. soap per piece.After again washing they are passed into weak sulphuric sours, 1° Tw., at 100“to 110° F., washed again, and dried.

The prolonged dippings involve a great outlay of time and labour andrender the China blue style costly. A saving of expense is effected byforming the dippings by machinery instead of by hand, but the quality of" thework is inferior. In addition this style does not admit of the highest degreeof sharpness and delicacy of design.

A process which admits of the execution of delicate patterns is the whitedischarge style for indigo blues, invented by Mr. J. Mercer. The process isbegun by dyeing the pieces in a uniform blue in the vat, generally a mediumshade. They are next washed and padded with a solution of bichrome, at6° T. They must now be dried in a current of cold air, and in the shade,sunshine—or even strong indirect light—and an elevated temperature beingequally fatal to success. They are then printed with the following :—

No. 5. White Discharge .—

Water. 1 gal.

Flour . 2 lbs.

Dark British gum . 2 „

Boil up and mix thoroughly, and when nearly cool add—

Oxalic acid. 2 lbs.

And when quite cold—

Sulphuric acid .. ..'.7J ozs. (measure).

This mixture rapidly removes the vat blue, leaving only a whitish-grey. Thepieces are then nearly dried, and winced first in a mixture of ground chalkand water, then in weak sulphuric acid sours, at 2° Tw., then in water. Theyare next well washed and dried, when the discharged portions will be found ofa pure white. If the pieces have been exposed to sunlight after the chromingprocess, or dried too sharply at an elevated temperature, the blues arespoiled.

Indigo Greens, or Dipped Greens, are now in less request than formerly.In producing them either white cloth, or cloth printed and dyed with maddercolours, is printed with No. 5 or 6 (Style V.) by block or machine as mostappropriate. The green dipping is next effedted as follows :—The pieces passfirst through an ordinary light blue vat; then after travelling some yards inthe air to secure oxidation, they enter a lead vat, composed of 250 lbs. brownsugar of lead and 130 lbs. of dry slaked lime, dissolved in 1000 gals, of water.They then enter a third vat of water alone, and pass finally through a vat ofsolution of bichrome, at 4° Tw., which brings up a yellow with the lead, andthus converts the blue into a green.

Seventh Style.—Discharges on Turkey-Reds.

No. 1. White Discharge (Machine ).—

Tartaric acid solution, at 62° Tw. 1 gal.

Acetic acid, at 6° Tw. 1 ,,

British gum (light) . 8 lbs.